CHEMIC.\L PROPERTIES OF F.\TTY ACIDS AKT) REL.\TED COMPOUNDS 13") 



Another general procedure for anhydride synthesis involves the action 

 of oxalyl chloride on the acids in benzene solution. This method is es- 

 pecially satisfactory with aromatic acids, ^^^ but it gives poor yields with the 

 aliphatic acids. ■'^^ However, better results are obtained with oxalyl chlo- 

 rides on the aliphatic fatty acids when their sodium soaps are used. 



Ketene, CH2:C:0, combines with the higher fatty acids to give a mixed 

 acetic anhydride.''^* On subsequent distillation of the mixed anhydride at 

 high temperatures, the two symmetrical anhydrides result. 



Table 46 



Melting Points and Boiling Points of Simple Anhydrides of S.\turated and 



Unsaturated Fatty Acids 



" Data from A. W. Ralston, Fatty Acids and Their Derivatives, Wiley, New York, 

 1948, p. 799. 



* Superior figure indicates the barometric pressure in millimeter of mercury at which 

 the boiling point was determined. 



' W. Blevberg and H. Ubrich, Ber., B64, 2504-2513 (1931). 



"^ F. Krafft and F. Tritschler, Ber., 33, 3580-3585 (1900). 



' D. Holde and K. Rietz, Ber., B57, 99-102 (1924). 



/ D. Holde and C. Wilke, Z. angew. Chem., 35, 105; 289-291 (1922). 



e D. Holde and K. Schmidt, Z. angew. Chem., 35, 502-503 (1922). 



'' D. Holde and R. Gentner, Ber., B58, 1067-1071 (1925). 



b'. Properties of Acid Anhydrides: As noted earlier, the melting 

 points of the anhydrides of the aliphatic acids have a wider range than do 

 those of the fatty acids, being lower in short-chain and higher in the long- 

 chain compounds than those of the corresponding fatty acids. All of the 

 anhydrides below capric acid are liquids at ordinary temperatures. The 

 more volatile short-chain compounds can be distilled at ordinary pressure 



«2 R. Adams, W. V. Wirth, and H. E. French, J. Am. Chem. Soc, 40, 424-431 (1918). 

 "93 R. Adams and L. H. Ulich, J. Am. Chem. Soc., 42, 599-611 (1920). 

 «" C. D. Hurd and M. F. Dull, J. Am. Chem. Soc, 54, 3427-3431 (1932). 



